Organic-dispersible lanthanide fluorides nanocrystals were synthesized at a large scale using colloid-extraction method, in the presence of dialkyl-dithiophosphinic acid (DDPA) as the extraction agent. The products we...Organic-dispersible lanthanide fluorides nanocrystals were synthesized at a large scale using colloid-extraction method, in the presence of dialkyl-dithiophosphinic acid (DDPA) as the extraction agent. The products were characterized by means of X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transformation infrared (FTIR) spectroscopy. It was found that the synthesized lanthanide fluorides nanoparticles had high purity and crystallinity, and could be well dispersed in organic solvents such as chloroform, toluene etc., which could be closely related to the surface-capping of the nanocrystals by the DDPA molecules. Moreover, the nanocrystals before and after extraction by DDPA showed few differences in the microscopic morphologies. It was implied that DDPA as the extraction agent had good protection to the nanocrystals as well, which could be essential to the commercial application of the titled rare earth nanocrystals as novel multifunctional additives in the fields of lubrication.展开更多
This paper investigates the uplink spectral efficiency of distributed cell-free(CF)massive multiple-input multiple-output(mMIMO)networks with correlated Rayleigh fading channels based on three different channel estima...This paper investigates the uplink spectral efficiency of distributed cell-free(CF)massive multiple-input multiple-output(mMIMO)networks with correlated Rayleigh fading channels based on three different channel estimation schemes.Specifically,each access point(AP)first uses embedded pilots to estimate the channels of all users based on minimum mean-squared error(MMSE)estimation.Given the high computational cost of MMSE estimation,the low-complexity element-wise MMSE(EW-MMSE)channel estimator and the least-squares(LS)channel estimator without prior statistical information are also analyzed.To reduce non-coherent and coherent interference during uplink payload data transmission,simple centralized decoding(SCD)and large-scale fading decoding(LSFD)are examined.Then,the closedform expressions for uplink spectral efficiency(SE)using MMSE,EW-MMSE,and LS estimators are developed for maximum ratio(MR)combining under LSFD,where each AP may have any number of antennas.The sum SE maximization problem with uplink power control is formulated.Since the maximization problem is non-convex and challenging,a block coordinate descent approach based on the weighted MMSE method is used to get the optimal local solution.Numerical studies demonstrate that LSFD and efficient uplink power control can considerably increase SE in distributed CF m MIMO networks.展开更多
0 INTRODUCTION Due to the rapid population growth and the accelerated urbanization process,the contradiction between the demand for expanding ground space and the limited available land scale is becoming increasingly ...0 INTRODUCTION Due to the rapid population growth and the accelerated urbanization process,the contradiction between the demand for expanding ground space and the limited available land scale is becoming increasingly prominent.China has implemented and completed several largescale land infilling and excavation projects(Figure 1),which have become the main way to increase land resources and expand construction land.展开更多
As a new member in two-dimensional materials family,transition metal carbides(TMCs)have many excellent properties,such as chemical stability,in-plane anisotropy,high conductivity and flexibility,and remarkable energy ...As a new member in two-dimensional materials family,transition metal carbides(TMCs)have many excellent properties,such as chemical stability,in-plane anisotropy,high conductivity and flexibility,and remarkable energy conversation efficiency,which predispose them for promising applications as transparent electrode,flexible electronics,broadband photodetectors and battery electrodes.However,up to now,their device applications are in the early stage,especially because their controllable synthesis is still a great challenge.This review systematically summarized the state-of-the-art research in this rapidly developing field with particular focus on structure,property,synthesis and applicability of TMCs.Finally,the current challenges and future perspectives are outlined for the application of 2D TMCs.展开更多
Deep-seated large-scale toppling failure presents unique challenges in the study of natural slope deformation process in mountainous regions.An active deep-seated toppling process was identified in the Erguxi slope lo...Deep-seated large-scale toppling failure presents unique challenges in the study of natural slope deformation process in mountainous regions.An active deep-seated toppling process was identified in the Erguxi slope located in southwest China,which affected a large area and damaged critical transportation infrastructure with the volume of the deforming rock mass exceeding 24×10~6 m^3.It poses significant risks to the downstream Shiziping Hydropower Station by damming the Zagunao River.Field investigation and monitoring results indicate that the deformation of the Erguxi slope is in the advanced stage of deep-seated toppling process,with the formation of a disturbed belt but no identifiable master failure surface.It was postulated that the alternating tensile and shear strength associated with the hard/soft laminated rock strata of metasandstone and phyllite layers preclude the development of either a tensile or shear failure surface,which resulted in the continuous deformation and displacement without a catastrophic mass movement.The slope movement is in close association with the unfavorable geological conditions of the study area in addition to the construction of transportation infrastructure and the increase of the reservoir level.On the basis of the mechanism and intensity of the ongoing toppling deformation,a qualitative grading system was proposed to describe the toppling process and toevaluate the slope stability.This paper summarized the field observation and monitoring data on the toppling deformation for better characterizing its effect on the stability of the Erguxi slope.The qualitative grading system intends to provide a basis for quantitative study of large-scale deep-seated toppling process in metamorphic rocks.展开更多
In the paper, the problem of H∞ decentralized state feedback control for largescale systems is described. An algorithm is proposed which uses the method of a feasible direction matrix. The algorithm only requires the...In the paper, the problem of H∞ decentralized state feedback control for largescale systems is described. An algorithm is proposed which uses the method of a feasible direction matrix. The algorithm only requires the solution of an algebraic Riccati equation (ARE) and makes the H∞norm of the closedloop transfer function matrix from disturbance inputs to controlled outputs less than a given constant which ensure the stability of the overall controlled system at each iteration. The given example shows that the convergence of the algorithm is satisfactory.展开更多
This study aimed to develop the seasonal forecast models of Korean dust days over South Korea in the springtime. Forecast mode was a ternary forecast （below normal, normal, above normal） which was classified based o...This study aimed to develop the seasonal forecast models of Korean dust days over South Korea in the springtime. Forecast mode was a ternary forecast （below normal, normal, above normal） which was classified based on the mean and the standard deviation of Korean dust days for a period of 30 years （1981-2010）. In this study, we used three kinds of monthly data： the Korean dust days observed in South Korea, the National Center for Environmental Prediction in National Center for Atmospheric Research （NCEP/NCAR） reanalysis data for meteorological factors over source regions of Asian dust, and the large-scale climate indices offered from the Climate Diagnostic Center and Climate Prediction Center in NOAA. Forecast guidance consisted of two components; ordinal logistic regression model to generate trinomial distributions, and conversion algorithm to generate ternary forecast by two thresholds. Forecast guidance was proposed for each month separately and its predictability was evaluated based on skill scores.展开更多
Metalens is the next generation of optical metasurfaces for compact imaging,sensing,and display applications that allow the phase,polarization,frequency,amplitude,angular momentum,etc.of the incident light to be desig...Metalens is the next generation of optical metasurfaces for compact imaging,sensing,and display applications that allow the phase,polarization,frequency,amplitude,angular momentum,etc.of the incident light to be designed with high degrees of freedom to meet the application requirements,which has attracted broad interest in the field of planar optics.One significant challenge in implementing applications for metalens is the efficient fabrication of largescale nanostructures with high resolution,robustness and uniform patterning.In this review,we first introduced the manufacturing techniques compatible with metasurfaces fabrication in detail,including masked lithography,maskless lithography,and additive manufacturing,discussed the limitations and provided some insights.Next,we introduced the applications of metalens from the perspective of non-imaging and imaging optics fields.Metalens can enhance the illumination effect,shape beams,and improve the energy conversion efficiency in non-imaging optics.In imaging optics,the role of metalens in replacing traditional optical components in lithography,astronomical observation,microscopic and endoscopic systems is demonstrated.Finally,the challenges that the metalens facing on the road to commercial application are discussed,and the field’s future development is prospected.展开更多
We propose a nonmonotone adaptive trust region method based on simple conic model for unconstrained optimization. Unlike traditional trust region methods, the subproblem in our method is a simple conic model, where th...We propose a nonmonotone adaptive trust region method based on simple conic model for unconstrained optimization. Unlike traditional trust region methods, the subproblem in our method is a simple conic model, where the Hessian of the objective function is approximated by a scalar matrix. The trust region radius is adjusted with a new self-adaptive adjustment strategy which makes use of the information of the previous iteration and current iteration. The new method needs less memory and computational efforts. The global convergence and Q-superlinear convergence of the algorithm are established under the mild conditions. Numerical results on a series of standard test problems are reported to show that the new method is effective and attractive for large scale unconstrained optimization problems.展开更多
Solid-state potassium metal batteries have increasingly gained attention as promising alternatives in largescale energy storage due to their safety and low cost.However,these batteries usually suffer from a lack of su...Solid-state potassium metal batteries have increasingly gained attention as promising alternatives in largescale energy storage due to their safety and low cost.However,these batteries usually suffer from a lack of suitable K^(+)conducting solid electrolytes.Herein,a new KB_(11)H_(14)·2Me_(3)NBH_(3) complex electrolyte with high ionic conductivity and relative stability against K metal is reported.The crystal structure was solved as a monoclinic P2_(1)/c lattice.Density functional theory(DFT)calculations confirm significantly enhanced K-ion diffusion in the structure.High K-ion conductivities of 2.63×10^(-6) S cm^(-1) at 25℃ and 3.25×10^(-4) S cm^(-1) at 75℃ are achieved,putting it among the leading K^(+)solid conductors.Moreover,it shows favorable interfacial stability against the K metal anode precoated with NH_(3)B_(3)H_(7).Batteries coupling the TiS_(2) cathode deliver long-term cycling stability.This work provides a new group of K-ion solid-state electrolytes for safe potassium metal batteries.展开更多
基金Project supported bythe National Natural Science Foundation of China (20401006)Natural Science Foundation of Henan Province (200510475019)
文摘Organic-dispersible lanthanide fluorides nanocrystals were synthesized at a large scale using colloid-extraction method, in the presence of dialkyl-dithiophosphinic acid (DDPA) as the extraction agent. The products were characterized by means of X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transformation infrared (FTIR) spectroscopy. It was found that the synthesized lanthanide fluorides nanoparticles had high purity and crystallinity, and could be well dispersed in organic solvents such as chloroform, toluene etc., which could be closely related to the surface-capping of the nanocrystals by the DDPA molecules. Moreover, the nanocrystals before and after extraction by DDPA showed few differences in the microscopic morphologies. It was implied that DDPA as the extraction agent had good protection to the nanocrystals as well, which could be essential to the commercial application of the titled rare earth nanocrystals as novel multifunctional additives in the fields of lubrication.
基金supported by National Natural Science Foundation of China(NSFC No.62020106001)。
文摘This paper investigates the uplink spectral efficiency of distributed cell-free(CF)massive multiple-input multiple-output(mMIMO)networks with correlated Rayleigh fading channels based on three different channel estimation schemes.Specifically,each access point(AP)first uses embedded pilots to estimate the channels of all users based on minimum mean-squared error(MMSE)estimation.Given the high computational cost of MMSE estimation,the low-complexity element-wise MMSE(EW-MMSE)channel estimator and the least-squares(LS)channel estimator without prior statistical information are also analyzed.To reduce non-coherent and coherent interference during uplink payload data transmission,simple centralized decoding(SCD)and large-scale fading decoding(LSFD)are examined.Then,the closedform expressions for uplink spectral efficiency(SE)using MMSE,EW-MMSE,and LS estimators are developed for maximum ratio(MR)combining under LSFD,where each AP may have any number of antennas.The sum SE maximization problem with uplink power control is formulated.Since the maximization problem is non-convex and challenging,a block coordinate descent approach based on the weighted MMSE method is used to get the optimal local solution.Numerical studies demonstrate that LSFD and efficient uplink power control can considerably increase SE in distributed CF m MIMO networks.
基金funded by the Key Research and Development Program of Shaanxi Province(No.2024SFYBXM-669)the National Natural Science Foundation of China(No.42271078)。
文摘0 INTRODUCTION Due to the rapid population growth and the accelerated urbanization process,the contradiction between the demand for expanding ground space and the limited available land scale is becoming increasingly prominent.China has implemented and completed several largescale land infilling and excavation projects(Figure 1),which have become the main way to increase land resources and expand construction land.
基金This research was supported by grants from by the National Natural Science Foundation of China(52002254)Sichuan Science and Technology Program(2020YJ0262,2021YFH0127)+2 种基金Chunhui plan of Ministry of Education of China,Fundamental Research Funds for the Central Universities,China(YJ201893)State Key Lab of Advanced Metals and Materials,China(Grant No.2019-Z03)the Danish National Research Foundation and EU H2020RISE 2016-MNR4S Cell project.
文摘As a new member in two-dimensional materials family,transition metal carbides(TMCs)have many excellent properties,such as chemical stability,in-plane anisotropy,high conductivity and flexibility,and remarkable energy conversation efficiency,which predispose them for promising applications as transparent electrode,flexible electronics,broadband photodetectors and battery electrodes.However,up to now,their device applications are in the early stage,especially because their controllable synthesis is still a great challenge.This review systematically summarized the state-of-the-art research in this rapidly developing field with particular focus on structure,property,synthesis and applicability of TMCs.Finally,the current challenges and future perspectives are outlined for the application of 2D TMCs.
基金financially supported by the National Natural Science Foundation of China (Grant No.41572302 and Grant No.41130745)the Funds for Creative Research Groups of China (Grant No.41521002)the Open Research Fund from the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection (Chengdu University of Technology) (Grant No.SKLGP2015K001)
文摘Deep-seated large-scale toppling failure presents unique challenges in the study of natural slope deformation process in mountainous regions.An active deep-seated toppling process was identified in the Erguxi slope located in southwest China,which affected a large area and damaged critical transportation infrastructure with the volume of the deforming rock mass exceeding 24×10~6 m^3.It poses significant risks to the downstream Shiziping Hydropower Station by damming the Zagunao River.Field investigation and monitoring results indicate that the deformation of the Erguxi slope is in the advanced stage of deep-seated toppling process,with the formation of a disturbed belt but no identifiable master failure surface.It was postulated that the alternating tensile and shear strength associated with the hard/soft laminated rock strata of metasandstone and phyllite layers preclude the development of either a tensile or shear failure surface,which resulted in the continuous deformation and displacement without a catastrophic mass movement.The slope movement is in close association with the unfavorable geological conditions of the study area in addition to the construction of transportation infrastructure and the increase of the reservoir level.On the basis of the mechanism and intensity of the ongoing toppling deformation,a qualitative grading system was proposed to describe the toppling process and toevaluate the slope stability.This paper summarized the field observation and monitoring data on the toppling deformation for better characterizing its effect on the stability of the Erguxi slope.The qualitative grading system intends to provide a basis for quantitative study of large-scale deep-seated toppling process in metamorphic rocks.
基金theNational+4 种基金 Natural Science Foundation of China
文摘In the paper, the problem of H∞ decentralized state feedback control for largescale systems is described. An algorithm is proposed which uses the method of a feasible direction matrix. The algorithm only requires the solution of an algebraic Riccati equation (ARE) and makes the H∞norm of the closedloop transfer function matrix from disturbance inputs to controlled outputs less than a given constant which ensure the stability of the overall controlled system at each iteration. The given example shows that the convergence of the algorithm is satisfactory.
基金supported by the project "Development and Application of the Techniques on Asian Dust Monitoring and Prediction" of National Institute of Meteorological Research/Korea Meteorological Administration in 2011
文摘This study aimed to develop the seasonal forecast models of Korean dust days over South Korea in the springtime. Forecast mode was a ternary forecast （below normal, normal, above normal） which was classified based on the mean and the standard deviation of Korean dust days for a period of 30 years （1981-2010）. In this study, we used three kinds of monthly data： the Korean dust days observed in South Korea, the National Center for Environmental Prediction in National Center for Atmospheric Research （NCEP/NCAR） reanalysis data for meteorological factors over source regions of Asian dust, and the large-scale climate indices offered from the Climate Diagnostic Center and Climate Prediction Center in NOAA. Forecast guidance consisted of two components; ordinal logistic regression model to generate trinomial distributions, and conversion algorithm to generate ternary forecast by two thresholds. Forecast guidance was proposed for each month separately and its predictability was evaluated based on skill scores.
基金supported in part by the Natural Science Foundation of Zhejiang Province under Grant(ZCLZ25F0502)in part by the Science and Technology Innovation Leading Talent Project of Special Support Plan for High-level Talents in Zhejiang Province(2021R52032)+2 种基金in part by the China Jiliang University Basic Research Expensesin part by the Zhejiang University Students Science and Technology Innovation Activity Plan—New Talent Plan(2024R409C054)in part by the Scientific Research Fund of Zhejiang Provincial Education Department(Y202456390).
文摘Metalens is the next generation of optical metasurfaces for compact imaging,sensing,and display applications that allow the phase,polarization,frequency,amplitude,angular momentum,etc.of the incident light to be designed with high degrees of freedom to meet the application requirements,which has attracted broad interest in the field of planar optics.One significant challenge in implementing applications for metalens is the efficient fabrication of largescale nanostructures with high resolution,robustness and uniform patterning.In this review,we first introduced the manufacturing techniques compatible with metasurfaces fabrication in detail,including masked lithography,maskless lithography,and additive manufacturing,discussed the limitations and provided some insights.Next,we introduced the applications of metalens from the perspective of non-imaging and imaging optics fields.Metalens can enhance the illumination effect,shape beams,and improve the energy conversion efficiency in non-imaging optics.In imaging optics,the role of metalens in replacing traditional optical components in lithography,astronomical observation,microscopic and endoscopic systems is demonstrated.Finally,the challenges that the metalens facing on the road to commercial application are discussed,and the field’s future development is prospected.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant No. 11171159）,the Specialized Research Fund of Doctoral Program of Higher Education of China （Grant No. 20103207110002）, the Fund for Innovative Program of Jiangsu Province （Grant No. CXLX12_0387）, CNPq-Brazil （Grant No. 301748/ 2011-0）, and the Research Fund of Pontifical Catholic University of Parana, Brazil.
文摘We propose a nonmonotone adaptive trust region method based on simple conic model for unconstrained optimization. Unlike traditional trust region methods, the subproblem in our method is a simple conic model, where the Hessian of the objective function is approximated by a scalar matrix. The trust region radius is adjusted with a new self-adaptive adjustment strategy which makes use of the information of the previous iteration and current iteration. The new method needs less memory and computational efforts. The global convergence and Q-superlinear convergence of the algorithm are established under the mild conditions. Numerical results on a series of standard test problems are reported to show that the new method is effective and attractive for large scale unconstrained optimization problems.
基金supported by the National Natural Science Foundation of China(Grant No.U18042532,U23A2078,22171246,92261203,and 22273053)。
文摘Solid-state potassium metal batteries have increasingly gained attention as promising alternatives in largescale energy storage due to their safety and low cost.However,these batteries usually suffer from a lack of suitable K^(+)conducting solid electrolytes.Herein,a new KB_(11)H_(14)·2Me_(3)NBH_(3) complex electrolyte with high ionic conductivity and relative stability against K metal is reported.The crystal structure was solved as a monoclinic P2_(1)/c lattice.Density functional theory(DFT)calculations confirm significantly enhanced K-ion diffusion in the structure.High K-ion conductivities of 2.63×10^(-6) S cm^(-1) at 25℃ and 3.25×10^(-4) S cm^(-1) at 75℃ are achieved,putting it among the leading K^(+)solid conductors.Moreover,it shows favorable interfacial stability against the K metal anode precoated with NH_(3)B_(3)H_(7).Batteries coupling the TiS_(2) cathode deliver long-term cycling stability.This work provides a new group of K-ion solid-state electrolytes for safe potassium metal batteries.
